2007 DODGE GRAND CARAVAN SXT, 3.8 ENGINE, 61K CAME INTO SHOP WITH P0300/P0301/P0303/P0305 MISFIRE CODES, FAILING EMISSION TEST. CUSTOMER HAD NOT REPLACED PLUGS AT 30 OR 60K, SO WE STARTED WITH PLUGS AND WIRES. AFTER DRIVING FOR ABOUT 1000 MILES, THEY CALLED WITH A REPORT OF POWER LOSS/ENGINE SURGING...